Chip Resistor Part Number Tail Code for Romania: 1,392 Walsin Rows End in a Power Letter and a TCR Letter

The chip resistor part number tail code is a lookup table nobody has published. We parsed all 234,815 Walsin chip resistor rows for buyers in Romania: 1,392 part numbers end in a two-letter tail, the first letter sets rated power, the last sets TCR, and not one row breaks either mapping.

Strip the tail and you strip a rating. On 1,388 Walsin chip resistors the 12-character stem exists as a separate part, and the tailed twin is rated higher on every one of them. Venatech Limited, an authorised Walsin distributor in Hong Kong, holds all 137 chip resistor export files published by Walsin Technology (Walsin). This post is written from the Part Number, Rated Power and TCR columns of those files, read as raw strings. Every part number below is real and sits in the export. For a buyer in Romania the question is simple: what does the code after FTL actually select?

What is the two-letter code after the stem of a Walsin chip resistor part number?

A power class and a TCR class, in that order. We measured the length of every part number: 159,228 have 12 characters, 74,195 have 13 and 1,392 have 15, in which the last two or three characters are a tail. 996 of the 1,392 put a space before the tail (WR20F1R00FTL HN) and 396 attach it with a leading J (WW20WR050FTLJHN). They sit in nine prefixes, WR12, WR20, WR25 and WW06 to WW25, across four series.

We have not seen this counted anywhere. Five power letters map to five wattages and five TCR letters map to five TCR grades, and the mapping is one-to-one in both directions across all 1,392 rows. No letter ever appears against two values. That is a complete lookup table, recovered from the data alone.

Which letter is the power class?

D, F, G, H and J, standing for 1/4 W, 1/2 W, 3/4 W, 1 W and 2 W. We cross-tabulated the first tail letter against the Rated Power column. The mapping holds across sizes, which is what makes it a code and not a coincidence: F is 1/2 W at both 0805 and 1206, and G is 3/4 W at both 1206 and 1210.

Five letters, five wattages, 1,392 rows, zero disagreements. We read these in Thick_Film_Low_Ohm_Current_Sense_Chip_Resistor__1of1.xlsx, which holds 972 of them, and in four general purpose files, Thick_Film_General_Purpose_1_1_2W.xlsx, Thick_Film_General_Purpose_1_2W.xlsx, Thick_Film_General_Purpose_1_1W.xlsx and Thick_Film_General_Purpose_5.xlsx, which hold the other 420.

Which letter is the TCR class?

N, L, K, J and H, standing for ≦±100, ≦±200, ≦±400, ≦±600 and ≦±1000 ppm/°C. We cross-tabulated the last tail letter against the TCR column. N is by far the most common, at 1,114 rows, because it covers the 1.00 ohm general purpose parts and the 0.050 ohm current sense parts alike.

Read the two tables together and a tail like GH decodes without a lookup: 3/4 W and ≦±1000 ppm/°C, which is exactly what WW12WR010FTL GH publishes at 1206 and 0.010 ohm. The code is also compact, which is presumably why it exists: it lets one stem carry five power ratings and five TCR grades without a new series.

Does the tail change the part, or only decorate it?

It changes the rating, every time. We took the 12-character stem of each of the 1,392 tailed numbers and looked for it as a part number of its own. 1,388 of the 1,392 exist as tail-less parts, and on all 1,388 the tailed twin has the higher rated power: 748 at double, 306 at one and a third times, 168 at 2.25 times and 166 at 1.125 times. The TCR differs on 92 of the same 1,388 pairs. The four without a twin are WW20WR025FTL HJ, WW20WR025JTL HJ, WW10WR025FTL GK and WW10WR025JTL GK.

A BOM tool that strips everything after FTL, or that treats the space as a delimiter and keeps the first token, collapses each pair into one line and silently keeps the lower rating. Our note on why Walsin part numbers do not paste into your BOM covers the 39,576 numbers that contain a space; these 996 are the ones where the part after the space is not padding.

What does the tail not tell you?

Which datasheet governs it, and what J means in four places. We hold 28 Walsin datasheets, 451 pages, and two are chip resistor sheets. The WR sheet, ASC_WR_V24 dated September 2016, prints 1/4 W for WR12 and covers neither WR20 nor WR25, so the 140 WR12 rows at 1/2 W are outside what it states. The catalogue-number key on page 3 of each sheet ends at the termination code L, after size, type, resistance, tolerance and packaging, and prints no power or TCR letter beyond it.

The letter J also does four jobs in the strings we parsed. As the thirteenth character it appears on 46,449 rows, and as a leading tail letter it appears on 396. As a power letter it means 2 W, on 308 rows, and as a TCR letter it means ≦±600, on 72. The thirteenth-character J is not an automotive flag either; see the automotive letter rule that misreads 10,209 parts.

What should a buyer in Romania do with a tailed part number?

Keep the whole string, and read the rating from the tail: the 12-character stem alone selects a lower rating on 1,388 of 1,392 parts. Before a tailed part number enters your library, three checks cost under a minute each.

1. Keep the full 15 characters. Do not split on the space and do not trim to 12. The stem alone selects a part with a lower power rating in 1,388 of 1,392 cases.
2. Read the power and TCR letters against the two tables above, then confirm the same values in the Rated Power and TCR fields of the export row.
3. Paste your list into the free cross-reference tool. It decodes 18 manufacturers’ part numbers, takes up to 500 at a time or an Excel or CSV file, and states every difference from your original rather than hiding it.

For the power-rating picture across all 19 case sizes, see chip resistor power rating by case size. For the sheet that governs WR12, see the WR datasheet revision note. What is in Hong Kong is on ready stock: 1,125 part numbers as at 23 September 2026, a dated snapshot and not a live feed. The range sits on the Walsin chip resistor page. Our address is Unit 207, 2/F, Sun Ling Plaza, 30 On Kui Street, Fanling, N.T., Hong Kong, telephone (852) 2628 4777. Confirm against both datasheets and qualify in your own circuit.

The short version

1,392 of 234,815 Walsin chip resistor part numbers end in a tail: 996 after a space, 396 attached with a leading J. The first letter is a power class (D, F, G, H, J for 1/4, 1/2, 3/4, 1 and 2 W) and the last is a TCR class (N, L, K, J, H for ≦±100 to ≦±1000), with zero exceptions on either. 1,388 of the 1,392 stems also exist as tail-less parts, and the tailed twin is rated higher on all 1,388. We will not tell you a tailed part matches its stem. We will show you the rating the tail selects. Qualification stays with you.

Send us the chip resistor lines off your bill of materials and we will flag every one whose part number carries a tail, with the stem rating beside it. And a question back: when your tool trimmed a Walsin part number to its first 12 characters, did anyone check which power rating survived?

Frequently asked questions